!6 2 TEXT-BOOK OF FUNGI 



CHEMISTRY OF FUNGI 



SUGARS 



Mannite, trehalose, and glucose have been found in 

 many kinds of fungi by Bourquelot ; of these the two 

 first named are crystallisable. Mannite occurs most 

 generally ; glucose is often present in young specimens, 

 becoming partly transformed into mannite as the fungus 

 matures. 



The following genera are characterised by the presence 

 of trehalose : Cortinarius, Coprinus, Hypholoma, Hebeloma, 

 and Pholiota. Mannite alone is present in Russula, 

 Ladarius, Psalliota, Lepiota, and Peziza. The relative 

 distribution of sugars is constant and characteristic of 

 certain genera. 



Bourquelot gives the proportion of saccharine matters 

 present in one kilogram of fresh tissue, from various parts 

 of Boletus edulis. Stem, 24-5 grams of trehalose, and 077 

 gram of glucose. Pileus, 13*8 grams of trehalose, 0*71 

 gram glucose. Saccharine matters are absent from the 

 tubes. This distribution of sugars is considered to explain 

 why the larvae of Diptera are confined in their attacks to 

 certain portions of a fungus. 



FATS AND OILS 



These bodies are often present as reserve substances, in 

 many reproductive bodies, as oospores and zoospores of Chy- 

 tridiaceae and Saprolegniaceae, uredospores, basidiospores, 

 ascospores, etc. Large quantities are also often present in 

 the mycelium, that of Lactarius deliciosus containing about 

 six per cent. Sclerotia also, as a rule, contain large quan- 



